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Sunday, February 17, 2008

XML is 10

The XML Recommendation is celebrating its 10-year anniversary, that is, the anniversary of the official publication of the Recommendation on 10 February 1998. However I think of XML as really starting in 1996, when the activity was revealed publicly for the first time at the SGML 2006 conference. I wrote about XML and its development at that anniversary here: Dr. Macro's XML Rants: XML: Ten Year Aniversary (And I discovered this post, which I had totally forgotten about, when I googled "sgml 1996 conference" in order to verify that my memory of the dates was correct. How sad is that? [or conversely, how cool is that?--you choose.]).

I will re-iterate what I said two years ago: while Tim Bray and Michael Sperberg-McQueen, as the editors of the XML 1.0 Recommendation, are most publicly associated with the XML it was Jon Bosak who made XML happen. It was Jon who put the "SGML on the Web" working group together, personally invited all the initial members, set the working rules that allowed us to work quickly and productively, and managed the political and procedural process of getting XML through the W3C. Jon knew what he wanted and knew the ingredients that were needed and knew how to put them together in a way that would most likely produce the desired result. In that sense he was like a chef producing a dish dependent on the complex interactions of different ingredients, a dish that is not a simple assembly task but one that involves carefully managed reactions and cooking times applied to a variety of ingredients where quality was a key determining factor.

Without Jon's drive, judgment, and leadership, the XML development process could have easily bogged down or been derailed in any number of ways. It would have taken only one spoiler or resistance from inside the W3C or simple poor management of the process to kill or delay the whole thing.

It's also important to remember that what we developed as XML represents absolutely no technical innovation. There is nothing in the XML 1 Recommendation that isn't in SGML, with the possible exception of well-formedness being sufficient (since SGML required the use of DTDs with document instances). The genius of XML, and the challenge in developing the spec, was figuring out what to leave out of XML. Each of us on the Working Group had our pet features, without which we felt XML would be at best crippled, at worst useless. I think we did a remarkably good job of not including features that were not essential.

In retrospect, I wish we had gone farther and left out DTDs and entities entirely, but of course that would not have been politically acceptable at the time and there would have been nothing to replace DTDs with (in fact, I still find it amazing that the XSD spec was ever finished given the challenge inherent in developing that specification given the wide range of requirements and constituencies driving it).

I think it's also fair to say that XML has succeeded far beyond any of our initial expectations. All we really wanted was a way to publish SGML data using Web technology. It never occurred to us that it would be embraced as a general-purpose data structuring and program-to-program communication format (for good or ill). I've always found it a little annoying that the vast majority of data using XML has nothing or little to do with documents in the sense of information intended primarily for human consumption. Whatever.

I suppose prognostication is expected at this point.

Where do I see XML going in the next 10 years?

I think it's fair to say that XML is entrenched and unlikely to be replaced any time soon. It's hard to imagine that any group would have the motivation and resources to build a general-purpose XML alternative given XML works more than well enough for most of the applications to which it is put. From an engineering standpoint, it would be a case of overoptimization.

In the domain of structured documentation I think that the DITA standard in particular will accelerate the adoption of XML for docment representation. The values have been well understood for decades and they aren't going to change. Because DITA, leveraging XML's deep and ubiquitous infrastructure, lowers the cost of entry of using XML for sophisticated document representation it can only serve to bring more enterprises and users to XML, users for whom in the past an SGML or even XML solution would have been prohibitively expensive. I find that very exciting. I don't remember well enough to know if that particular effect of XML was envisioned or even hoped for, but I think we all, even at that time, understood to some degree the power that Web technology had in general to make things easier and cheaper. But certainly lowering the cost of building XML parsers was a primary design driver, our mythical "graduate student with a weekend" to build a parser. That vision has definitely been realized.

In the domain of program-to-program communication it would not surprise me if something specifically designed for that task supplants XML, something like JSON. This is a domain where, because there is no particular great body of data, but only processing code, APIs, and support libraries, the engineering equation would make optimization more attractive: there's no question that XML is not the best solution for character-based serialization of arbitrary objects and data structures. I certainly wouldn't object to proposals to replace XML with JSON for those applications. The key is to understand that XML is still the best available solution for persistent data. I think a lot of people who use XML day to day forget (or never were told) that XML, via SGML, was originally designed to facilitate search and long-term, application-independent archiving of data. It is almost coincidence that makes that same application-independence useful for communication of transient data. Convenient but not optimal.

I fully expect to be able to do more or less what I'm doing now ten or twenty years from now. Whether I will be is another question, but so far, just when I thought I was completely bored of it, something new in the XML world has come along to re-energize my interest. And we're still struggling to build truly useful XML-aware hyperdocument management systems. Hopefully that won't be the case in 2018.

And lets not forget Dr. Charles Goldfarb, who's own singleminded passion, drive, and leadership produced SGML, without which XML (and HTML, for that matter) would never have happened. SGML turned 20 in 2006. It's largely now forgotten except by a few early adopters who have been using their SGML-based systems productively for ten or fifteen years now and had no compelling business reason to move to XML. But I remember.

Kids today....

1 Comments:

Anonymous Anonymous said...

This isn't relevant to this post but wasn't sure where to post on your blog. I wanted to see if you have ran across Intel's XML software products and have evaled them to give them your review?

http://www.intel.com/software/xml

11:25 PM  

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